NEOWISE spotted from Alki Beach

Last night, July 14, 2020, was a pleasantly mild one on Alki Beach in West Seattle, and it turned out to be a perfect on during which to catch a glimpse of Comet C/2020 F3, to which we will henceforth refer as NEOWISE.

I wandered down to the beach with my binoculars and my DSLR camera a little past 9pm to stake out a good spot for comet searching. It turned out to be way earlier than was necessary. Scanning often with the binoculars, I didn't finally spot the comet until right around 10:30pm. Once spotted it was still pretty faint, but at the same time easy to find again.

Shot of Comet NEOWISE from Alki Beach on July 14, 2020.
Photo: Greg Scheiderer

I'm not often accused of being an astrophotographer, though I sometimes like to get a snapshot just to prove I was there. In this case, as the weather forecast looked favorable for the evening I must have read a dozen articles during the day about how to photograph a comet. This gave me about two dozen techniques from which to choose, but enough ballpark information that I thought I would be able to get a decent shot. The one directly to the left is my favorite from the evening.

An unexpected challenge of getting this shot is that NEOWISE was so faint that I couldn't really frame the photos through the camera viewfinder or with the back screen. I ended up taking images, and if the comet wasn't there, I'd just move the camera a bit, take another one, and another, until I found a composition that I liked.

NEOWISE from Alki
Photo: Greg Scheiderer

It worked out pretty OK!

For the photog types out there, I used a Nikon D3100 with the 55-200mm zoom kit lens. I was at ISO 1600. The upper photo was a 10 second exposure at f4.2 with the lens at 66mm. The one to the left was at 55mm, eight seconds at f4.

I found several shots that were zoomed in a little closer to be a tad blurry. It was pretty hard to set focus!

Comet hunting was fun and I was a bit surprised that there were so many folks out who were aware of this event, many of them back for a second evening at Alki. My binoculars gave lots of folks a better look, so that was enjoyable.

NEOWISE was the most impressive comet I've seen. Back in early 2007 Comet McNaught was spectacular, but mostly a Southern Hemisphere event. I caught it briefly one evening as it moved between the clouds right around sunset. Hale Bopp was great in 1996-97, but I don't remember being able to see so much of it's tail, at least when I saw it. I was in college when Comet West was here and still haven't figured out how I missed that entirely.

NEOWISE will be around for a few more weeks. This NASA site has good info for spotting it.

An evening with famed comet hunter Don Machholz

In an age when automated programs are scanning the night sky using high-tech telescopes, CCD cameras, and computing power to find near-Earth objects, Don Machholz continues to search for comets the old-fashioned way.

Seattle Astronomy’s Greg Scheiderer, left, with comet hunter
Don Machholz at the Seattle Astronomical Society’s annual
banquet. Photo: Greg Scheiderer.

“I do it visually,” Machholz explained at the annual banquet of the Seattle Astronomical Society last month. “I do not use cameras, I do not use CCDs. I look through the eyepiece and I push the telescope.”

Machholz is the record holder, with eleven comets discovered visually since he started his hunt in the mid-1970s. That doesn’t sound like so many, but consider this: according to the Catalog of Comet Discoveries, there have been 1,502 comets discovered since 2005. Of those, just three have been discovered visually. The Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) got full or shared credit for thirty-three comet discoveries last year alone. The last time a comet was discovered visually was in 2010, when there were two, and Machholz bagged one of those.

There’s a little bit of luck involved in comet hunting. Machholz jokes that the first thing you need to do to find a comet is to be looking where it is in the 40,000 square degrees of sky. But he has a system. He checks websites to figure out where the programs like Pan-STARRS are looking on a particular night and then conducts his hunt in a different part of the sky. Machholz divides the sky into sections, and makes telescope sweeps covering about fifteen degrees at a time. Then moves down about a half field of view and sweeps again. He keeps meticulous records of his searches.

“It sounds boring, but you get to see a different part of the sky all the time,” Machholz said.

He got interested in astronomy as a boy. His father was a naval navigator and had a book with star charts that Don used to learn the sky. When he was about eight years old his sister brought home a book about meteors that piqued his interest. Finally, Machholz received a telescope for his thirteenth birthday. On the third night out he found Saturn.

“I could see the rings on it,” he recalled, thinking stargazing might not be such a bad hobby. He was hooked.

A family tragedy helped drive Machholz’s comet-hunting program early on. In 1976 his brother, an avid skier, was killed in an avalanche. Machholz found himself depressed, with insomnia, sleeping just a few hours a night, but with lots of energy.

“That’s kind of the ideal ingredients for a comet hunter,” he said. “For the next three or four years my comet hunting program developed to a greater and greater depth. Comet hunting wasn’t just something I did, it became part of who I am.”

His early comet hunting was done from his parents’ back yard and other locations around Concord, California. After moving to San Jose in 1976 he did much of his observing from nearby Loma Prieta mountain. In 1990 he moved to Colfax, California and built an observatory there.

After so much time at the eyepiece, Machholz says his heart still skips a beat or two when he thinks he has found a new comet.

“It’s a very important moment,” he said. “First I want to remember what song was on the radio.” He always has the radio playing when he hunts, and his presentation was full of music from the Rolling Stones and the Beatles to Phil Collins and Cyndi Lauper. He adds, though, that there’s no time for jumping up and down when he finds a comet, because there’s serious work to do.

“You don’t want to lose it,” he explained. “You might have it in the field now, but if you bump the telescope or let too much time go by and it drifts out of the field, you have to be able to find it again.”

“You have to be sure you know where you’re looking, make sure it’s not a galaxy or a cluster,” he added. He double checks with his star atlas, makes a drawing that puts the comet in its position compared to the field of stars, and watches to see if it moves. If all that checks out he reports the discovery by email, phone, and fax.

Comet 96/P Machholz as seen by the 

HI-2 camera on the STEREO-A spacecraft.

Of all of his discoveries, Machholz said comet is 96P/Machholz is his favorite.

“It is an amazing comet; it has its own Facebook page,” he said.

The orbit of 96/P Machholz changes because of the influence of Jupiter, and the perturbations have some scientists thinking there may be large undiscovered planets way out beyond Pluto. The comet also is low on carbon and cyanogen. This hasn’t been explained, though the leading ideas are that it may have originated in another solar system, or been exposed to temperature extremes that changed its chemical composition.

It was a pleasure to spend an evening with Don Machholz. His lively presentation was full of humor and had the banquet audience laughing and engaged.

PanSTARRS peeks through Seattle clouds

Persistence in the face of clouds has paid off for a number of Seattle-area stargazers, including your faithful correspondent, who have managed to spot comet PanSTARRS over the last couple of days.
As sunset approached yesterday things were looking hopeful in the west from West Seattle, though there were clouds building on the horizon. Seattle Astronomy dashed down to the south end of Alki Beach Park, near the Charles Richey Sr. Viewpoint, to hunt for PanSTARRS. Binoculars in hand, I swept the areas between the clouds and–Eureka!–finally spotted the comet, probably around 8:10 p.m., as I posted this tweet at 8:17:

Success! PanSTARRS spotted from West Seattle!

— Seattle Astronomy (@SeattleAstro) March 17, 2013

I am still amazed at the little gasp of discovery I get whenever I spot a new celestial object, or even familiar ones. I probably had 10 minutes of viewing, maybe a little more, before PanSTARRS was swallowed up by a large black cloud, not to be seen again. It was a pretty sight, with a definite tail shooting up maybe a degree or two. I would rank it my second-best ever city comet, after the spectacular McNaught of 2007, which was spotted under similar circumstances between clouds that year.

I was not able to see PanSTARRS with the naked eye yesterday, though I expect had there been just a few more minutes for it to get a little darker, I could have. I may try again this evening; as I write this, a little after noon, the sky is mostly clear. But a lot can change between now and sunset, about six hours hence.

This Sky & Telescope diagram and article are a good guide
for viewing Comet PanSTARRS, at least for the next few days.

March 16 was the scheduled date for the Seattle Astronomical Society‘s monthly public star parties and, as often happens, both were officially canceled because of the weather. There were, however, reports on the club’s Google Group Through the Clouds that an ad hoc group ditched the usual star party site at Green Lake and spotted PanSTARRS from Sunset Hill Park. Other club members wrote in and reported sightings from Redondo Beach in Des Moines, the Des Moines Marina, Lowman Beach Park in West Seattle, and Hazlewood Elementary School in Newport Beach.

Sorin, the Soggy Astronomer, posted several photos from the evening on his Flickr stream. Jason Enevoldsen caught a photo the day before, posted by his spouse on her Alice’s Astro Info site. The Enevoldsens were planning to be down at Seattle’s Lincoln Park last night, though we’ve received no dispatches as of this moment.

So, keep hunting, Seattle comet seekers! It can be done. PanSTARRS is getting further from the Sun, and thus fainter, each day. But good views should be had for a while yet.

Avoiding asteroid armageddon

NASA’s chief asteroid hunter says one spectacular comet and two lousy motion pictures are probably the reasons that we are keeping a close watch for asteroids or comets that could potentially smack into Earth and wipe out life on our planet.

“The collision of comet Shoemaker-Levy 9 with Jupiter in 1994 sensitized the public to impacts in the solar system,” said Don Yeomans, senior research scientist and manager of the Near-Earth Object Program Office at the Jet Propulsion Laboratory. “Then there were those two dreadful movies around 1998—’Armageddon’ and ‘Deep Impact.’ They sensitized the public. The public contacted their Congressmen, their Congressmen said, ‘NASA, what the heck are you doing about this problem?’”

Thus were born the agency’s efforts to track near-Earth objects.

Yeomans, author of Near-Earth Objects: Finding Them Before They Find Us, spoke last week at Town Hall Seattle. He must know his stuff; after all, he’s got an asteroid—2956 Yeomans—named after him! Yeomans gave an engaging presentation about the history of rocks slamming into our planet, from the football-sized meteorite that wrecked a New York woman’s Chevy Malibu in 1992 to the 10-kilometer asteroid that nailed us 65 million years ago and snuffed the dinosaurs. He noted that asteroids and comets probably delivered the water and carbon-based materials to the early Earth that allowed life to form, but they could potentially destroy life, too.

Yeomans’ job is to make sure that doesn’t happen. He says an army of professional and amateur observers are tracking thousands of near-Earth objects and feeding the data to JPL.

“It’s up to us to compute orbits for all of these objects and run their motions a hundred years into the future to see if any of them make any interesting close-Earth approaches,” Yeomans said. JPL then figures the likelihood of any of these objects actually hitting the Earth.

“If any objects represent a threat we ask for additional observations from the observing community,” Yeomans explained, adding that this helps them pin down an object’s orbit. “As we get more and more data the uncertainties get smaller and smaller and we can run that for a couple of hundred years into the future to see if it is actually going to hit the Earth.”

Yeomans said the probability of something hitting us is not zero.

“There are almost 100 objects on our risk page for which we cannot yet rule out an Earth impact,” he said. “But all of the impact probabilities are very small—one in 10 to the sixth or smaller—so no one should lose sleep over near-Earth objects coming in and taking us by surprise. Still, there are a number of them that we’re keeping an eye on.”

The good news is that there is something we can do about it if we discover an object on a collision course with Earth. In fact, it’s a relatively simple maneuver that we’ve already pulled off: send up a spacecraft and ram it into the thing.

“You could slow it down a millimeter per second and change its orbital period, so in 10 to 20 years when it was predicted to hit the Earth it would miss by a wide margin,” Yeomans said.

His biggest concern is with a comet impact. Comets often aren’t discovered until they reach the orbit of Jupiter. It takes a comet just nine months or so to get from Jupiter to Earth, so if one were headed for us there would be little time to do anything. The good news is that asteroids far outnumber comets, and so a comet impact is a much more remote possibility.

Earlier this month NASA ruled out the chances that the asteroid Apophis will slam into us in 2036, though it will miss Earth by less than 20,000 miles in 2029. Yeomans said they will keep a constant eye out for other near-Earth objects.

“We need to find them before they find us if we are indeed to have a future,” he said.
UPDATE: Speaking of asteroids and Yeomans, Alice’s Astro Info has posted about Asteroid 2012 DA14, which is going to miss us by that much Feb. 15.

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Listen to a recording of Yeomans’ talk on the Town Hall Seattle website.